The name of this control system represents its constituent parts the proportional, integral and derivative terms. PID controlĪ PID control system aims to remedy the issue with the proportional controller demonstrated above. After finely tuning the gain, a proportional controller might be acceptable in some applications, but it would make for a very nauseating flight for Jeb and may even shake the craft apart. The reduction of the amplitude of these oscillations is due only to the damping in the system from air resistance. The controller is only aware of the current error in the system so it keeps wildly overshooting the set state and the point ends up oscillating around the set state. Moreover, it should be possible to maneuver the craft in 3D space without having any control of the yaw axis (although it will be pointing in a random direction).įigure 4 : Modelling a proportional controllerįigure 4 shows how this system evolves over time there is a clear issue. This will be discussed more later, but controlling this axis shouldn't be necessary to achieve stable flight. This design has one considerable drawback over a conventional quadcopter, in that there is no way to control the yaw of the craft. Note, we don't need any engine gimballing because we will steer the craft by varying the thrust across the 4 engines.įor the design I will be using, please see Figure 1. In Kerbal Space Program, this means sticking with liquid rocket engines such as the 48-7S "Spark". Secondly, we need the engines to be highly responsive to change in thrust because we will be constantly altering them to keep the craft flying level. Firstly, the craft should be as symmetric and balanced as possible more precisely, the centre of mass and centre of thrust should be as close as possible so that the craft doesn't flip over straight away. To be in with the best chance, the vessel should satisfy a few design requirements.
The goal of this project was to design, build and attempt to control a rudimentary "quadcopter" in the video game Kerbal Space Program. So the question arises, how can we vary the speeds of each motor to stabilise and control the aircraft? Such questions are normally answered in an environment such as MATLAB with Simulink but the video game Kerbal Space Program and addon kRPC provide a fun sandbox in which to experiment. In practice, with inevitable discrepancies in design and manufacture, producing such a perfectly symmetric system is impossible. In a theoretical setting, applying equal power to each motor should cause the vessel to rise straight up. Drone and quadcopter usage is at an all time high, but controlling them isn't exactly plain sailing.